Miss Gloomy loses head (4)
I believe the answer is:
lack
'miss' is the definition.
(lack can mean to be missing)
'gloomy loses head' is the wordplay.
'gloomy' becomes 'black' (I've seen this before).
'loses head' means to remove the first letter.
'black' with its initial letter taken away is 'LACK'.
(Other definitions for lack that I've seen before include "Deficiency or want" , "Dearth" , "Deficiency (of something)" , "Absence, deficiency" , "Be wanting or without" .)